This proposal is for a clinical center in collaborative trial that is designed to assess the feasibility, acceptability, efficacy, and safety of dietary intervention designed to reduce low density lipoprotein (LDL) levels in children ages eight years to ten years identified as having elevated LDL cholesterol levels. The Center for Health Research and the study investigators have conducted a variety of studies relevant to the proposed study. These include several collaborate trials of diet intervention and behavior modification, and a variety of therapeutic and demonstration projects in reducing health risk. The primary source of participants at the Portland Center will be the membership of Kaiser Permanente, Northwest Region. This HMO enrolls 300,000 members, approximately 20% of the Metropolitan Area. The Kaiser Permanente membership closely resembles the metropolitan population. Kaiser Permanente has effectively served as a primary recruitment source for the MRFIT, BHAT, and SHEP trials. The clinical center will, during the feasibility phase, recruit and randomize 20 free-living, previously untreated prepubescent children ages 8-10 with high LDL cholesterol. These children and their families will be randomized into a dietary intervention group and a usual care control group. During the full trial the center will recruit and randomize 80 children and their families to study and control groups. The study group will be offered a diet intervention program, to assess the acceptability, efficacy, and safety of the intervention. Because health-related habits are so resistant to change and because the family is a primary factor in the initial learning of health-related attitudes and behaviors, the intervention is designed to involve children and their families simultaneously.